1. Field of the Invention
The present invention relates to an optical disk drive unit having a magnet, a yoke and a movable coil.
2. Description of the Related Art
In a general optical disk drive unit, a magnetic circuit for performing a seeking operation is disposed in a carriage and is composed of a movable coil, a magnet and yokes symmetrically arranged with respect to the optical axis of an objective lens. Further, bearings for fixedly supporting the carriage and a guide rail for supporting the bearings are arranged outside the magnetic circuit for performing a seeking operation. The guide rail moves the carriage in a seeking direction. Therefore, this optical disk drive unit has disadvantages that the size of the carriage is increased in a width direction thereof perpendicular to the seeking direction.
Further, it is necessary to dispose a space portion for receiving an inside yoke located on a side of the movable coil near the carriage. This space portion is formed to extend in a height direction of the carriage. Furthermore, it is necessary to set the height of the carriage to be suitable in accordance with the space portion. It is also necessary that the distance between the carriage and a moving part of the objective lens and located above the carriage is set to be suitable in accordance with the space portion. Therefore, the height of the carriage cannot be reduced.
Therefore, in the general optical disk drive unit, the weight of a movable section such as the carriage movable in the seeking direction is increased so that it takes time to move the carriage in the seeking direction and perform an accessing operation with respect to information.